Which cause is naturally prior. On the number of causes.

One inquires further into which cause is naturally prior. And it seems to be the material cause. Because what is un-generated and incorruptible is prior to that which is corruptible and able to be generated. But matter is of this sort, and form is not, and the same holds true for the efficient and the final cause, and therefore, etc.

It seems to be the efficient cause. Because that which is the cause of all other things appears to be prior. But the efficient cause is like this, and therefore, etc.

It seems to be the final cause. Because that which moves first is the first cause. But the final cause is like this, and therefore, etc.

It seems to be the form. Because ens and esse precede all other things. Therefore, that which is the first cause of being [esse] is first among the causes. But the form is like this, and therefore, etc.

And the same sort of inquiry can be made into the number of causes.

To the first, one must reply that something is prior to something else in two ways: either in completion or in generation. With respect to completion, the final cause is prior and the efficient cause is second, while the form is third, and the matter is last, because the efficient cause is called a cause only because it moves. But it moves only because it is moved earlier by the final cause. Thus, the final cause [finis] is the reason that there is an efficient cause. In addition, one generating generates one like itself. Therefore, the reason that the form of the one generated is as it is, is that the efficient cause was as it was. Therefore, the efficient cause is the reason why a form such as this is introduced. But matter is for the sake of form. Therefore, the final cause moves the efficient, and the efficient determines the form, and the form determines its matter. But the path of generation is just the opposite, because in order for something to come to be, first an agent is required, and, second, something on which it may act is required, and once these are present, it produces an effect. But it acts only by intention, and this is why the intent follows last, and why the efficient cause is first, and then the matter (as one undergoing some change [ patiens]), and third is the form that is introduced, and last is the end which is intended, because the end is that which follows as a consequence.

In this way a solution to the arguments is evident.

One must reply to the second argument in a variety of ways, because each thing's cause is either internal or external. If it is external, then it is either the "cause by which," and this is the efficient cause, or it is the "cause for the sake of which," and this is the final cause. If it is internal, either it is act, and this is the form, or it is potency, and this is matter.

Or, in another way: Every cause is either a cause of being or a cause of becoming. If it is a cause of being, since being [ ens] is divided into act and potency, then it is either a cause of being in actand thus form is as a prior thingor it is a cause of being in potencyand thus is matter. If it is a cause of becoming, then it is either an operating cause, and this is the efficient cause, or it is that for the sake of which it operates, and this is the final cause.

The Philosopher solves this in another way in the second book of the Physics where he says that "there are as many causes as there happen to be ways of inquiring why [propter quid] something occurs." But it happens that there are four ways in which one can inquire why something happens, and this is why there are four [causes], etc. So much for this point.

Whether the Philosopher ought to treat the mode of dividing here.

One further inquires whether the Philosopher ought to treat the mode of dividing here.

1. And it seems not. For the Commentator, in the second book of the Metaphysics, says it is inappropriate to seek to teach and to inquire into the mode of teaching at the same time. But in this book the Philosopher divides the animals, and as a result treating the mode of dividing is not part of this book's task.

2. Moreover, it is one thing to build a plough and altogether something else to use a plough, according to the Philosopher in the second book of the Physics. Therefore, for the same reason, it is one thing to treat the mode of dividing and another thing altogether to use division.

The contrary is apparent if one follows the determination made by the Philosopher.

One must reply that some divisions follow after properties of form and others follow after properties of matter. The first division pertains to logic and to first philosophy, that is, metaphysics, but the second division pertains to physics. This is why the Philosopher does not use the first division here but only the second mode of dividing, for he divides "animal" into blooded and bloodless and into winged and not-winged. And these are material divisions, and this is why they can be pertinent to the natural philosopher. Generally one can say that there is a threefold order of proceeding in science, namely, an order of division, definition, and synthesis:[1] Division is with respect to the genus, definition with respect to the species, and synthesis with respect to the properties and accidents. And these modes pertain to logic as far as teaching goes, but with respect to their actual use they can belong to other branches of philosophy. Therefore, the fact that the Philosopher treats here the art of defining is not with respect to the physical world but with respect to form, and here he dons and arms himself with the habit of the logician, and this is why, etc.

[1] "Synthesis": collectivus, which suggests a process of gathering and collecting data.